I just put a Mikuni HSR 42 on. I was running WAY too rich with my CV. I changed the plugs and ran about 120 miles Sunday and here's what I found. Plugs are clean as a whistle...no marks or colorization at all. The metal still looks like metal, porcellin, too.

The bike really runs great with no backfiring or carbfarting. The only thing is a very slight ping when I do a WOT roll-on from about 3,000 rpm. It doesn't lug at all. It starts going strong for about 500 rpm and then just a few scattered pings the rest of the way up. It really hauls ass, though.

I haven't touched the out of the box settings except the idle. Does this sound like I should raise the needle or...?

If so, how the hell do you do that? I have bigger main jets that came with it and they're easier to change.

I just did same mod ...my end settings are 1 size bigger on main jet.. needle, moved clip to raise 1 needle 1 notch ...runs great plugs look perfect but its only been in the 50's here I'm thinking I might have to lean it out once summer gets here . You might be spot on with your settings once it warms up ..hope this helps

p.s. they made a really good " mikuni sticky " I must have read it 20 times

Read that sticky alot, too. Basically, I'm waiting for my NRHS top end to get here. I'm worried that if I'm a bit lean now, with 94 octane gas and cold weather, when I go to 10.5:1, cams, and stage 2 heads, I'll be way too lean. Can't dyno it for 500 miles so I don't want to blow the whole thing up while I wait.

I figure I'll just richen up the main jet now (easy fix) and see. Looks like raising the needle is more work so I'll skip that until after my build.

I don't know SQUAT about Mikunis, and even LESS about the new ignitions, but I'd check your ignition settings with someone who knows first...that's what this sounds like...and ignition advance adjustment....

__________________~Chuck

"entia non sunt multiplicanda praeter necessitatem"

Occam's Razor...

in English: "entities must not be multiplied beyond necessity."
My definition: "The simplest answers are the most likely" ~NRHS machined 1200 conversion, shittin and gettin...